Method and apparatus for protecting electrical components from a transient electromagnetic disturbance

ABSTRACT

The present disclosure provides a method of protecting a component using a deliberately created impedance mismatch between conductive impedance transition elements and an electric power line. The method comprises coupling a plurality of conductive impedance transition elements having a greater diameter than the power line at a position between an extended length of the power line and the component. The difference between the diameters of the conductive transition elements and the power line causes an intentional impedance mismatch between the two or more impedance transition elements with adjacent portions of the power line, and the mismatch causes high-frequency components of the transient electromagnetic signals induced on the power line by the transient electrical disturbance to be reflected by at least one of two or more impedance transition elements away from the protected component.

TECHNICAL FIELD

The present invention relates to a method and apparatus for protectingelectronic equipment (electrical components (EC)) from hazardous EMIincluding transient electromagnetic disturbances, such as anelectromagnetic pulse whose origin may be a natural occurrence orman-made.

Definitions

Component: An individual electric or electronic element or a pluralityof such elements connected in a defined circuit or system.

Conductive Impedance Transition Element (CITE): A conductive elementcoupled to a conductor that has an abrupt increase in diameter relativeto the conductor.

Decaying Resonator: Two CITE elements or clusters of CITE elementspositioned on a conductor with spacing in between, wherein highfrequency components of an electromagnetic signal is caused to reflectback and forth between the CITE elements and continues such reflectionuntil the signal dissipates as heat. The spacing between the CITEelements is chosen such that electromagnetic signals in a selectedfrequency band do not collide and add via constructive interference.Electromagnetic Attack: A scenario wherein a hazardous EMI signal isintentionally inflicted on some electrical or electronic equipment orsystems with the intent to cause damage, disruption, or confusion ofsaid system.Electromagnetic Interference (EMI): Electromagnetic radiation thereception of which is undesired in an electrical system as it caninterfere with conveyed signals or equipment coupled to such system. EMIis defined herein as a broad term that encompasses numerous sub-typesthat are defined herein below.Electromagnetic Pulse (EMP): A transient burst of electromagneticradiation having a fast rise time of typically less than 5 nanosecondsthat is hazardous and can produce potentially damaging current andvoltage surges (and can thus be considered a subset of hazardous EMI).Typical EMP intensity is in the order of tens of thousands ofVolts/Meter. EMP can be produced by a nuclear detonation (NEMP; risetimetypically is less than 5 nanoseconds) or by non-nuclear sources thatproduce a suddenly fluctuating electromagnetic field such as coronalmass ejections (NNEMP; risetime typically is less than 5 nanoseconds).Electromagnetic Threat: A circumstance wherein a hazardous andintentional electromagnetic signal may be used against electrical orelectronic equipment or systems with the intent to cause damage,disruption, or confusion of said system.Extraordinary Electromagnetic Pulses: A class of EMP which encompassesall the various electromagnetic threats described herein, as previouslydefined in U.S. Pat. No. 8,300,378. Extraordinary EMP includes transientpulses arising from nuclear explosions (NEMP), non-nuclearelectromagnetic pulses (NNEMP) of sufficient strength to reach andrender inoperative components of an electrical power system, orgeomagnetically-induced current (GIC) as a result of coronal massejections from solar storms.Hazardous EMI: Electromagnetic interference the receipt of which in anelectrical system has a high likelihood of damaging or renderinginoperable electric equipment coupled to such system, such as, but notlimited to, electrical generating equipment, electronic circuit boardsand transformers. This interference may be a pulse or continuousemission.High-altitude Electromagnetic Pulse (HEMP): Also a subset of NEMP. HEMPis produced when a nuclear weapon is detonated high above the Earth'ssurface (exo-atmospheric), creating gamma-radiation that interacts withthe atmosphere to create an intense electromagnetic energy field that isharmless to people as it radiates outwardly but which can overloadcircuitry with effects similar to a lightning strike, but causing damagemuch more swiftly than a lightning strike.Intentional electromagnetic interference (IEMI): Electromagneticinterference intentionally (artificially) created to negatively affect atargeted electrical system. This interference may be a pulse orcontinuous emission.Narrow Bandwidth EM signal: An EM signal having a bandwidth that isequal to or less than 25 percent of the central frequency.Nuclear electromagnetic interference (NEMI): Electrical interferencecreated by detonation of a nuclear device and having an initial risetimeof less than 3 nanoseconds. NEMI includes fast rise-time electromagneticpulses (defined below) and radiation delivered with slower rise time andlonger duration. This is normally known as Electromagnetic Pulse (EMP)(see above).Power Line: An electrical power generation, transmission or distributionsystem having a power grid including multiple, synchronized sources ofpower generation. More particularly, the power line can comprise a“three-phase line” having three separate conductors, each of whichcarries a power signal in a phase-shifted relationship with the others.A fourth conductor can be neutral.Radio Frequency (RF): Electromagnetic emissions and signals in the radioportion of the spectrum, ranging from a few KiloHertz to many TeraHertz.Source Region Electromagnetic Pulse (SREMP): A subset of NuclearElectromagnetic Pulse (NEMP). A SREMP is produced by low-altitude(endo-atmospheric) nuclear burst. An effective net vertical electroncurrent is formed by the asymmetric deposition of electrons in theatmosphere and the ground, and the formation and decay of this currentemits a pulse of electromagnetic radiation in directions perpendicularto the current. The asymmetry from a low-altitude explosion occursbecause some electrons emitted downward are trapped in the uppermillimeter of the Earth's surface while others, moving upward andoutward, can travel long distances in the atmosphere, producingionization and charge separation. A weaker asymmetry can exist forhigher altitude explosions due to the density gradient of theatmosphere.System Generated EMP (SGEMP): SGEMP is a special class of EMP signalthat occurs as a result of energy reflecting within an equipmentenclosure. It is usually associated with and found within missiles butcan occur elsewhere. It is unique in that it is a secondary form of EMPemission.Ultrahigh Bandwidth EM signal: An EM signal having a bandwidth that isgreater than or equal to 75 percent of central frequency of the signal.

It is noted that NEMP, HEMP, SREMP, SGEMP, and others are allelectromagnetic pulses derived from the explosion of a nuclear device(fission, fusion, thermonuclear fusion). All are typified by extremelyfast risetimes, typically less than 5 nanoseconds, and can haverisetimes in the sub-nanosecond range. All these EMP types, as well asthe Non-Nuclear EMP class (NNEMP) produce pulses that are typified by anextremely broad RF Bandwidth, typically ranging from a few KiloHertz toseveral GigaHertz. It is further noted that the signal level at anyindividual frequency across this portion of the spectrum is not uniform,but the bulk of the energy is located below around 200 MegaHertz. Theseboundaries are not fixed and are determined by a number of parametersthat exist at the moment of the creation of said pulse.

BACKGROUND

It is well known that certain events can produce electromagneticradiation pulses that can be extremely destructive to electricalinfrastructure. The term used herein for this broad category ofelectromagnetic radiation is “hazardous electromagnetic interference(EMI).” In light of concerns regarding the spread of nuclear weapons andsimilarly destructive technology, research has been conducted to studythe effects of the powerful burst of hazardous EMI emitted by nucleardetonations (NEMI). Research has shown that nuclear detonations generatebursts of electromagnetic pulses (EMP) with extremely fast rise-times(on the order of less than 5 nanoseconds), followed by slower,longer-lasting portions of the signals which can last for a long periodof time, sometimes extending into minutes. One of the main determiningfactors in the ultimate shape of any nuclear derived EMP pulse is thealtitude at which it is detonated. Typical EMP intensity is in the orderof tens of thousands of Volts/Meter. This compares with the order of 200Volts/Meter for nearby radars, 10 Volts/Meter for communicationequipment, and 0.01 Volts/Meter for typical metropolitan area ambient.It is also noted that Federal Communication Commission (FCC) guidelinesmandate a limit of 0.5 Volts/Meter at the edge of the property line ofthe transmission cite for emissions of this sort.

Some of the characteristics of EMP which result in a threat toelectrical equipment are extremely fast risetime, extremely short pulsewidth, and field amplitude which gives rise to a signal with broadfrequency spectrum. There are three basic mechanisms for EM coupling toa conducting structure: electrical induction, the basic mechanism forlinear conductors; magnetic induction, the principal mechanism when theconducting structure forms a closed loop; and signal transfer throughthe earth (i.e. the physical planet). Devices which may be susceptibleto functional damage due to electrical transients include activeelectronic devices, passive electronic components, semiconductordevices, squibs and pyrotechnic devices, meters, and power systems,cables, electrical power grid switching and distribution elements.Operational upset and damage can be expected in digital processingsystems, memory units, guidance systems, and power distribution systems.Damage mechanisms include dielectric breakdown, thermal effects andinterconnection, switching, transformer and generator failures.

The spectral and energy distributions of a nuclear EMP of any typeprimarily depends on how high in the atmosphere that the detonationtakes place. Detonations take occur 40 km or less above the earth'ssurface, termed endo-atmospheric detonations, produce Source RegionElectromagnetic Pulses (SREMP), while detonations that occur 40 km orabove the earth's surface, termed exo-atmospheric detonations, produceHigh Altitude electromagnetic pulses (HEMP). SREMP is generated bycollisions between photons from gamma radiation and molecules of theatmosphere. These highly energetic photons eject electrons from thesurrounding air molecules, producing ionized air molecules. This immenseseparation of charge creates an intense E-Field which can be as high asseveral 100,000 Volts/Meter and has a large associated H-Field which canbe as high as 5000 Ampere-turns/Meter. FIG. 19A is a graph of anexemplary EMP waveform generated by an exemplary 100 KiloTonendo-atmospheric detonation over time. In FIG. 19A, the start of thewaveform (E1) of the SREMP is an extremely powerful pulse that rises toa maximum which can be as high as 250 KV/Meter in approximately 1nanosecond and falls to approximately 10 KV/Meter within 10 nanoseconds.In the scenario identified above, the electric field remainsapproximately constant at 10 KV/Meter in the second portion of thewaveform (E2) which lasts from the 10 nanosecond mark to about 100 μsafter the detonation. In the third portion of the waveform (E3) whichbegins at about 100 μs after the detonation, the electric field dropsfrom 10 KV/Meter to about zero by the 1 millisecond mark. FIG. 19B is agraph of the relative energy of the SREMP waveform versus frequency. Asshown, the frequency content of the SREMP waveform lies in a frequencyrange below 1 MHz, with the vast majority of the spectral content lyingbelow 10 kHz. It is noted that the exact field strengths, pulserisetimes, and duration depend upon a combination of multiple factorsincluding device geometry, device yield, height of explosion, andatmospheric conditions at the time of detonation.

In contrast, a HEMP is generated by gamma photons being absorbed byatmospheric molecules at altitudes above 40 Kilometers. This absorptioncauses electrons to be deflected by the earth's magnetic field into aspiral path about the field lines, causing them to radiateelectromagnetic energy. FIG. 20A is a graph of an EMI waveform generatedby an exemplary exo-atmospheric detonation over time. As shown, thewaveform of the HEMP is drastically different from its SREMPcounterpart. For devices in the 5 KiloTon to 1 MegaTon range, thiselectron radiated energy creates a large, diverse E-Field in the rangeof tens of KiloVolts/Meter and an associated H-Field in the range of 10to 300 Ampere-turns/Meter. Parts of the HEMP waveform can be of longerduration that SREMP, possibly lasting several seconds. As noted above,durations of specific parts of the waveform depend on a number offactors including device geometry, device yield, height of explosion,and atmospheric conditions at the time of detonation. FIG. 20B is aschematic graph of the relative energy of the HEMP waveform versusfrequency. As shown, about ninety percent of the energy is contained inthe 100 KHz to 10 MHz range.

EMP Versus Lightning

As mentioned above, the apparatus and methods disclosed herein protectagainst hazardous EMI including fast rise-time electromagnetic pulses(EMP) as well as relatively slower lightning strikes. For example, EMParising from endo-atmospheric denotations (SREMP) have a rapid rise time(typically sub-nanosecond) and short pulse duration (500 nanoseconds orless). This EMP has a substantial electrical field strength that istypically, but not limited to, the range of 10 KV/meter to 500 KV/meter.Electrical pulses in power lines generated by lightning behave in asimilar fashion to SREMP pulses, but have a slower risetime, typicallyaround 20 nanoseconds, and a longer pulsewidth than nuclear, or otherartificially created EMP. The consequence of this is that the low-Qdecaying resonators tend to be slightly less effective in suppressing atransient induced signal from lightning than they are in suppressing atransient induced signal from SREMP or non-nuclear sources. However, byadjusting the Q-factor of the decaying resonators in various embodimentsand arrangements it is possible to target extremely short EMP (SREMP) orlonger-pulse EMP (e.g., lightning) depending upon which type of EMP isdeemed to be the more important threat at a particular power line.

Conventional Protective Schemes

It should be noted that the majority of electromagnetic attack scenariosinvolve more than a single pulse being used in said attack. Theconsequence of this is that in order for a protective scheme to beviable, it must be able to withstand multiple sequential electromagneticattacks, possibly in close succession in order for such a protectivescheme to be considered as a viable means of protection. Some protectiveschemes are single shot or potentially single shot and thus are nottruly suitable for protection service, in spite of their currentwidespread use.

As noted above, in addition to the hazardous EMI generated by nucleardonations (SREMP and HEMP), electrical and electronic equipment can bedamaged by other events such as non-nuclear electromagnetic pulse,intentional electromagnetic bursts, coronal mass ejections (solarstorms) and lightning storms. Certain measures have been devised toprotect electrical systems from hazardous EMI. For example, conventionalsystems and devices for suppression of hazardous EMI such as EMP andlightning include, but are not limited to: electron tube protectivedevices, metal oxide varistor and other solid state devices, spark gaps,and inductors.

Electron Tube Protective Devices: The inventor of the presentapplication has previously developed protective means utilizing highspeed high power cold cathode field emission electron tubes as apreferred means for protecting electrical and electronic equipment fromdamage due to any of the aforementioned electromagnetic threats. Suchprotective cold cathode field emission electron tubes are described inU.S. Pat. No. 8,300,378 “Method and apparatus for protecting powersystems from extraordinary electromagnetic pulses” by Birnbach. Testingof this class of electron tube device has shown it to be suitable forprotective service in repetitive pulse applications with pulserepetition rates to over 500 KiloHertz.Metal Oxide Varistors (MOVs): MOVs are solid state devices which, intheir resting state, exhibit very high impedance, typically of, but notlimited to, 10 MΩ-100MΩ. When a voltage is applied across a MOV inexcess of some predetermined threshold, the MOV changes its internalimpedance to a very low impedance state. This allows the MOV to be usedto shunt overvoltages around critical circuit components. The speed atwhich this change of impedance occurs is a function of the specificdesign and material content of said MOV. A significant limitation of MOVdevices is that, since they are semiconductors, once a fault in thecrystalline structure of the substrate occurs, MOVs cannot be repairedand they do not self-heal. The foregoing type of fault is thepredominant failure mode of MOVs. As a result, MOVs cannot be relied onto provide protection for more than one overvoltage event. MOVs arecurrently the primary surge suppression means used by the publicutilities in spite of this limitation.

In addition, care needs to be taken in specifying a MOV because mostMOVs do not have a sufficiently fast risetime (typically approximately20 nanoseconds) to be useful in suppressing EMP from a nuclear explosion(NEMP), particularly the E1 portions of SREMP and fast-rise timeportions of HEMP. Even MOVs having fast reaction times adapted for highrise times (approx. 2-5 nanoseconds risetime) are still too slow to beeffective against all E1 pulses which typically have sub-nanosecond risetimes. This speed differential allows a devastatingly large amount ofenergy to pass before the protective action occurs, resulting in failureof the protected device and frequently of the protective device (MOV) aswell. Therefore, MOVs are generally not effective against NEMP.

There are some MOVs on the market which claim to be suitable for useprotecting against pulses in excess of 5,000 Amperes, even though theirconnecting wires are less than 0.125 inches (⅛″) in diameter. If thepulse were sufficiently short, less than one nanosecond in duration, theconnecting wires might not evaporate, but in any real-worldelectromagnetic attack scenario, the wires would evaporate thusrendering the device useless. It should be obvious to the person ofordinary skill in the art that the use of such devices is inadequate toprovide protection against real-world electromagnetic threats.

Other Semiconductor Devices: It is noted that there are a variety ofother semiconductor devices in use or in development for the transientsuppression application. An example of this is the gallium nitrideAvalanche Diode. This is a fast risetime switching diode withsufficiently robust parameters that when several are used together, ineither series or parallel depending on the specific application, thespeed of the group is slower than the speed of individual devices due toparasitic inductances and capacitances introduced by theinterconnections and the mandatory balancing network. All relevantsemiconductor devices are subject to failure due to failure of thecrystal structure associated with the piezoelectric effect.Semiconductor devices of this class are subject to the same failuremodes as MOV devices as discussed previously.Spark Gaps: A Spark Gap is a form of a fast switch which is sometimesused for hazardous EMI protection. A spark gap is wired to shunt theovervoltage around sensitive components. The threshold voltage isdetermined by the spacing of the electrodes of the spark gap. A problemwith spark gaps is getting them to trigger reliably at somepredetermined voltage. A further problem is that once fired, the contactsurfaces of the spark gap degrade by erosion, causing a change in theelectrode spacing, and subsequent firing events are usually not at thesame voltage as when the spark gap is new. Spark gaps require very highmaintenance and their use is generally restricted to laboratory pulsepower experimentation. Another form of spark gap that is usedexclusively by the electric power distribution and transmission industryis a set of specifically spaced curved rods, often referred to as“horns.” While too slow in risetime for protection against fast-risetime EMP, horns have been shown to be a simple approach for lightningprotection and are widely used. Their major disadvantage is that theyare easily damaged and require frequent replacement.Inductors: can suppress fast transient signals when wired in series witha circuit. The problem with the use of serially connected inductors asprotective devices is that the electrical insulation requirements andthe tolerance of the diameter of the conductor in the inductor, whichrelates to its ability to handle certain amounts of current withoutoverheating, are very strict, and serial inductors alone are generallynot capable of adequately suppressing hazardous EMI signals. The abilityof an inductor to withstand multiple repeated pulses is a function ofits design, specifically the insulation and thermal ratings. Inductorsconsume energy and are usually only used in sub-stations where surplusenergy is readily available.

Therefore, a need remains for a method and device that can reliably andefficiently overcome the foregoing deficiencies and protect electronicequipment from hazardous EMI.

SUMMARY

The present disclosure teaches a method and apparatus known as aConductive Impedance Transition Element (CITE), which, when properlyimplemented, provides a method of protecting a component mounted to apower line of an electrical power generation, transmission anddistribution system from hazardous EMI, which can include transientelectrical disturbances. The method comprises mounting a plurality ofconductive impedance transition elements (CITEs) having a diametergreater than diameter to the power line at a position between anextended length of the power line and the component. The differencebetween the diameters of the CITE and the power line causes an impedancemismatch between the two or more impedance transition elements withadjacent portions of the power line. This impedance mismatching causeshigh-frequency components of the transient electromagnetic signalsinduced on the power line by the hazardous EMI to be reflected back andforth between decaying resonators formed by pairs of conductiveimpedance transition elements. The decaying resonators dissipate theenergy of the high-frequency spectral portions of incoming hazardous EMIas heat. The low frequency spectral components, typically 50, 60 or 400Hertz, (standard electrical power distribution frequencies) are passedto the protected component. The method is particularly targeted fortransient electromagnetic disturbances having a rise time in a range of50 ps to 500 μS, but will work outside these ranges.

The plurality of conductive impedance transition elements have adiameter that is always greater than the power line. The ratio betweenthe diameter of plurality of conductive impedance transition elementsand the power line can be in a range of 1.5:1 and 100:1. A morerealistic ratio of the diameter of the plurality of impedance transitionelements to the diameter of the power line can be in a range of about2:1 to 80:1. Smaller and larger diameters can be used but are generallynot practical.

In certain embodiments, the plurality of conductive impedance transitionelements are formed in the shape of a disc. In further embodiments, theoutside of the disk has a radius that is larger than the thickness ofthe disk so as to form an anti-coronal structure, as is known to personsof ordinary skill in the art.

The plurality of conductive impedance transition elements can be groupedinto subsets each having two or more elements, an intra-element spacingbeing uniform within the subsets. In certain implementations at leastone of the plurality of impedance transition elements is positionedwithin preferably less than 100 meters of the component to be protected.

The plurality of impedance transition elements are designed to preventat least 75 percent of the transient electromagnetic signal induced onthe power line by the hazardous EMI from reaching the component. Thenumber of conductive impedance transition elements required is afunction of the desired degree of transient suppression and the spaceavailable for installation. The number of CITEs employed and thediametric ratio determines the degree of attenuation of the highfrequency components.

The present disclosure further provides a device for preventing orreducing the amplitude of an electrical signal induced on a power lineof an electrical power generation, transmission, and distribution systemgenerated by hazardous EMI from reaching an electrical componentconnected to the power line. The present invention comprises a pluralityof conductive impedance transition elements that are physically mountedon said power line and positioned between the electrical component and alength of power line upon which a transient electromagnetic signal isinduced by hazardous EMI. The plurality of conductive impedancetransition elements have a first side facing the length of power lineand a second side facing the electrical component, the first sides ofthe plurality of conductive impedance transition elements are sized todeliberately create an impedance mismatch with an adjacent portion ofthe length of the power line. The impedance mismatch causes the firstsides of the impedance transition elements to reflect the inducedtransient electromagnetic signals on the power line away from theelectrical component. The degree of impedance mismatch between theconductive impedance transition elements and the power line is afunction of the difference in diameters of the conductive impedancetransition elements and the power line itself.

The magnitude of the impedance mismatch is dependent upon frequency andpermits low frequency components of the induced transientelectromagnetic signal to pass by the plurality of conductive impedancetransition elements while reflecting high-frequency components of theinduced transient electromagnetic signal from the plurality of impedancetransition element.

To increase the efficiency of the conductive impedance transitionelements, one or more of the plurality of such conductive impedancetransition elements can be composed of or include sections of ferritematerial. Such ferrite materials can be incorporated either as aseparate disk unit or integrated into a conductive disk element.

It is noted that one or more of the CITEs may be constructed ofpartially or semi conductive materials, such as carbon, graphite, etc.This allows the disk to absorb a portion of the incident energy. Suchabsorbing CITEs may be used individually, in evenly spaced sets, inunevenly spaced sets, and other configurations as would be understood bya person of ordinary skill in the art.

It is further noted that the CITE assembly may be composed of acombination of conductive, absorbing, and ferritic materials, in varioussequences in order to achieve maximum suppression of the unwanted highfrequency portions of the signal.

A preferred embodiment of the plurality of conductive impedancetransition elements can have a dimension (e.g., diameter) that is atleast 1.5 times greater than a corresponding dimension of the powerline. In certain implementations, each of the plurality of impedancetransition elements has a diameter that is in a range of least 1.5 to100 times greater than the diameter of the power line, with a morepreferred diameter ratio range of 2 to 80. It is possible to useconductive impedance transition elements that are less than 2 times thediameter of the power line, with the understanding that the degree ofimpedance mismatch of each conductive impedance transition elements willbe less than if dimensions as specified for a preferred embodiment areused.

In certain implementations, each of the plurality of conductiveimpedance transition element comprises a first part and a second partthat is hingedly coupled to the first part and moves between an openposition and a closed position. Each of the first part and the secondpart of the conductive impedance transition element can have a fasteninghub surrounding a center opening for receiving the power line, a flatintermediate section, and a raised outer peripheral portion.

In certain implementations, each of the first part and the second partof the conductive impedance transition element includes a fastening hubincluding a center opening for receiving the power line, the fasteninghubs of the first and second part being adapted to fasten together tosecure the first and second part together when mounted on the powerline. See, for example, FIG. 12.

In certain implementations, the raised outer periphery can have atoroidal shape. The raised outer periphery can comprise a hollowstructure. The rationale for the raised outer periphery is to create astructure that minimizes the formation of coronal discharges inaccordance with well-known principles of art known to hypotheticalpersons of ordinary skill in the high voltage arts.

In certain implementations, the fastening hubs of the first and secondparts each include a semicircular portion and a rectangular footportion, the foot portions having matching threaded holes adapted forreceiving a fastening element. In a preferred embodiment, thesemicircular portions of the fastening hubs have inner surfaces bearingincision elements adapted for cutting into the power line and securingthe CITE to the power line. See FIG. 12

BRIEF DESCRIPTION OF THE DRAWING FIGURES

In the following drawing figures, like reference numbers refer to likeparts.

FIG. 1 is a schematic, prior art view of an electrical component (E.C.)which is connected to a power line (104) and which is susceptible todamage from a transient electromagnetic interference signal (14).

FIG. 2 is a schematic view, not to scale of a power line with anelectrical component that is protected (P.C.) by at least the oneillustrated conductive impedance transition element (CITE; 106, 107)from the destructive consequence of a transient electromagneticinterference signal according to the present disclosure.

FIG. 3 is a schematic view of another embodiment according to thepresent disclosure in which a power line is protected by two CITEs(125).

FIG. 4 is a modification of that portion of the arrangement of FIG. 3within a dashed-line rectangle.

FIG. 5 is a schematic view of another embodiment according to thepresent disclosure in which a power line is protected by three CITEs(178, 179).

FIG. 6 is a schematic view of another embodiment in which CITEsaccording to the present disclosure are used on a power line having afirst protected component (100) and a second protected component (102).

FIG. 7 is similar to FIG. 6, showing more general locations of CITEsprotecting the component on the left and more general locations of CITEsprotecting the component on the right.

FIG. 8 is a schematic view of another embodiment in which CITEs arearranged in groups of three (235) along the power line.

FIG. 9 is a plan view of one side of a first embodiment of a conductiveimpedance transition element (CITE) according to the present disclosure.

FIG. 10 is a plan view showing an upper component of the CITE pivotedwith respect to a lower component about a hinge element, showing thefirst embodiment in a partially open state to allow mounting onto anelectrical power conductor.

FIG. 11 is a hinge-end view of the first embodiment of the CITE.

FIG. 12 is a perspective view of the first embodiment of the CITEpartially open.

FIG. 13 is a perspective view of the lower component of the firstembodiment of the CITE.

FIG. 14 is a perspective view of the upper component of the firstembodiment of the CITE.

FIG. 15 is a longitudinal cross-sectional view of the first embodimentof the CITE taken through axis 15-15 in FIG. 11.

FIG. 16 is a plan view of one side of another embodiment of a CITEaccording to the present disclosure.

FIG. 17 is a perspective view of another embodiment of a conductiveimpedance transition element (CITE) according to the present disclosure.

FIG. 18A is a plan view of another embodiment of a CITE having anelliptical cross-sectional shape.

FIG. 18B is a plan view of another embodiment of a CITE having apolygonal cross-sectional shape.

FIG. 18C is a plan view of another embodiment of a CITE having anasymmetrical cross-sectional shape.

FIG. 19A is a graph of an EMI waveform generated by an exemplaryendo-atmospheric detonation (SREMP) over time. (From Sandia NationalLaboratory, hereinafter “Sandia”).

FIG. 19B is a graph of the relative energy of the SREMP waveform versusfrequency. (From Sandia).

FIG. 20A is a graph of an EMI waveform generated by an exemplaryexo-atmospheric (HEMP) detonation over time. (From Sandia).

FIG. 20B a graph of the relative energy of the HEMP waveform versusfrequency. (From Sandia).

FIG. 21 is a perspective view of another embodiment of a conductiveimpedance transition element (CITE) according to the present disclosureformed as a ferrite bead.

FIGS. 22A and 22B are plan views of longitudinal sections of a CITE,illustrating one embodiment of a method of assembling a CITE accordingto the present disclosure.

FIG. 23 is a perspective view of an alternative embodiment of a CITE,having a spherical shape.

FIG. 24 is a front plan view of a CITE having a transparent outerperipheral section filled with a fluorescent gas.

FIG. 25A-C show embodiments of CITE having central sections formeddifferent materials, respectively, an absorptive material such asgraphene (FIG. 25A), a metal such as aluminum (FIG. 25B), and a ferriticmaterial (FIG. 25C).

FIG. 26A is a perspective view of a first side of another embodiment ofa CITE according to the present disclosure having a metallic centralportion.

FIG. 26B is a perspective view of a second side of another embodiment ofa CITE according to the present disclosure having an absorptive centralportion.

FIG. 27A is an axial cross-sectional view of an underground coaxialpower cable having a semiconductor layer with differential impedancealong the length of the cable.

FIG. 27B is a longitudinal cross-sectional view of the undergroundcoaxial power cable shown in FIG. 27A.

FIG. 28A is a side view of another embodiment of a CITE having a tongueand groove for securing upper and lower components of the CITE.

FIG. 28B is a front plan view of the embodiment shown in FIG. 28A.

Further features and advantages of the invention will become apparentfrom reading the following detailed description in conjunction with thefollowing drawings, in which like reference numbers refer to like parts.The drawings and portions thereof are illustrative and are notnecessarily drawn to scale.

DETAILED DESCRIPTION

The devices (systems) and methods disclosed herein are configured toprotect electronic equipment, electrical components, and systems thereoffrom hazardous EMI including transient electromagnetic pulses (EMPs).

As mentioned previously, EMP was first noted in conjunction with nuclearexplosions; however, in recent years, it has become possible to generateEMP signals, comparable to or in excess of those generated by nuclearexplosions, by electrical means (man-made weapons and simulators).Electromagnetic pulses of concern are those in the range of typicallybut not limited to the range of 10 KV/meter to 500 KV/meter or higher.The apparatus and methods disclosed herein protect electricalinfrastructure against hazardous EMI including EMP arising from nuclear(NEMP) and non-nuclear (NNEMP) sources.

Deliberately Created Impedance Mismatch

The disclosed apparatuses (systems) and methods utilize the principle ofreflection of a significant portion of incoming hazardous EMI bydeliberate mismatch of impedances along a specified type of power line,where said hazardous EMI can be in the form of EMP or interferencesignal. Such “power line,” as used herein, can be that of an electricalpower generation, transmission or distribution system having a powergrid including multiple, synchronized sources of power generation. Moreparticularly, the power line can comprise a “three-phase line” havingthree separate conductors, each of which carries a power signal in aphase-shifted relationship with the others. A fourth conductor can beneutral. However, the systems and method can apply generally to the fullrange of phases used in electrical power distribution system rangingtypically from one to six or more in some cases. The number of phases ina system has no bearing on the use of CITEs technology other thanimposing a constraint that every phase including neutrals shall beequipped with one or more CITEs devices or sets of said devices,Reflections of significant portions of a hazardous EMI signal canprotect electrical components from being damaged and renderedinoperative by such signal. The intentional mismatch of frequencydependent impedance is realized by incorporating conductive impedancetransition elements (CITEs) on the power line. The CITEs can be thoughtof as being conductive attachments to the power line. The conductiveattachments (CITEs) can have the same cross-sectional shape as the powerline but have a diameter that is a number of times larger than thediameter of the power line.

Consider, for example, the total low frequency inductance of an elementof circular cross-section, which is

$L_{d\; c} = {2l*\left\lceil {{\ln\left( \frac{2l}{r} \right)} - {0.75}} \right\rceil}$

-   -   where:    -   L_(dc) is the “low-frequency” or DC inductance in nanoHenries        (nH or 10⁻⁹H);    -   l is the length of the element or structure in cm;    -   r is the radius of the element or structure in cm.        (E.B. Rosa, “The Self and Mutual Inductances of Linear        Conductors”, Bulletin of the Bureau of Standards, Vol. 4, No. 2,        1908, page 301ff.) The reactance (i.e., type of impedance) of an        inductor is        X _(L)=2πfL        from which it can be seen that a change to the radius of an        element, leads to an inductance (L) change, which, in turn,        causes proportional changes in impedance (X_(L)). The term “f”        here is the frequency of the signal input to the inductor. In        other words, an intentional change in variable r (radius of the        power line) due to the presence of an CITE on a power line to        r+x, in which x represents the positive diameter change of the        CITE over r, will cause a corresponding intentional mismatch of        impedance between an CITE and an adjacent length of power line        having the original value of r. The equation above also        indicates that any mismatch in impedance due to differences in L        is multiplied by the frequency value, with higher mismatches at        higher frequencies.

As one non-limiting example, if the power line comprises a 1-inchdiameter wire, the CITE can be configured as a disc having a 15 to 20inch diameter. This embodiment is suited for use in conventional powerline settings in which multiple power lines are typically strungside-by-side or one over another with sufficient distance between thepower lines. In particular, there are standards well known to persons ofordinary skill in the art that dictate the distance that separates eachpower line from another. It will be appreciated that since the CITE hasa greater width (diameter) than the power line, the CITE extendsoutwardly from a power line toward adjacent power lines. To avoid arcingor any other detrimental effects of having two conductors in closeproximity, a sufficient distance needs to be maintained between theoutward edge of the CITE and the adjacent power line or the peripheraledge of any CITE on the adjacent power line. Since power lines can swayaway from their tethering, shortening the distance between the adjacentlines, an extra tolerance is added to account for this phenomenon aswell. In some implementations, in the event of power lines that arespaced approximately 18 inches apart, the perimeter edge of the CITE ispositioned a prescribed distance from the adjacent power line, such asapproximately 6-12 inches. It is noted that it is a relatively simplematter to increase the distance separating the individual lines in apower transmission system to allow for the installation of CITEshardware.

Apart from the considerations regarding the spacing between power lines,the diameter of the CITEs also depends on the voltage level of the powerline. The higher the voltage used on the power line, the greater shouldbe the diameter of the CITEs mounted to the power line.

As discussed herein, exemplary implementations of the CITE includearrangements of two or more CITEs conjoined together as a unit andplaced along the power line. The efficiency of the overall system can bebased, at least in part, on the number of CITEs, or groups of CITEs, andthe spacing of said CITEs and groups of CITEs, that are arranged in apredetermined fashion along the power line.

Impedance mismatches result in standing waves along the transmissionline, a voltage standing wave ratio (VSWR) is defined as the ratio ofthe partial standing wave's voltage amplitude at an antinode (minimum)to the voltage amplitude at a node (maximum) along the line. The VSWR isa measure of the impedance match (or mismatch) of electrical sources andloads to the characteristic impedance of an electrical transmissionline. A high VSWR caused by the deliberate mismatch of impedancesbetween the CITEs or groups of CITEs and power line causes reflection ofthe high-frequency components (MHz to GHz range) of the incominghazardous EMI signal (e.g., EMP), but only weakly affects the much lowerfundamental frequency components of the current signal (e.g., 50-400 Hz)that supplies electrical power on the power line. The reflection of thehigh-frequency components of the transient signal is done to prevent (1)the destructive consequence due to voltage higher than the designvoltage of such components reaching and rendering inoperative amagnetic-winding containing electrical component connected to the powerline, such as a transformer, generator or motor by thermal or insulationdamage, and/or (2) the destructive consequence of such high-frequencycomponents reaching and rendering inoperative any deployed switchgearcomponents for interrupting current in the power line. It is noted thatother failure mechanisms are possible.

Implications of Destructive and Constructive Interference

It is noted that it is possible to deliberately create a situation wherethere is destructive or constructive interference of the reflectedtransient signals in said power line. It is important that considerationbe given to this matter when designing a CITEs system. Further, it isdesirable to optimize the CITEs system to deliberately createdestructive interference of the high frequency components to allow themto cancel themselves out independently of the normal operation of theCITEs system.

To ensure destructive interference, the spacing of the CITEs at oppositeends of the power line is not of a magnitude that gives rise toconstructive interference. In the case of installations where theprotected line can be powered down, a simple test can be conducted todetermine the optimum spacing.

In this test, a direct injection pulse source of suitable risetime,pulse width and amplitude is capacitively coupled to the power lineafter installation of the CITEs structures. A high speed oscilloscopewith a minimum of 1 GHz instantaneous bandwidth is coupled to the lineon the other side of one of the CITE structures. A pulse is injected andthe waveform is observed. If the pulse is reduced in amplitude ascompared from a sampled pulse from the injection side of the power line,then the spacing is appropriate. If the pulse is greater, then one setof CITE structures needs to be moved until the minimum pulse size isobserved. This test is also how a power line is certified to verifyproper operation of the CITE structures.

FIG. 1 is a schematic view of a system, not to scale, in which anelectrical component (E.C.) (electrical or electronic equipment) 10 isconnected to a power line 104 of an electrical power generation,transmission, and distribution system according to the prior art. Powerline 104 is shown with cross-hatching to indicate that it iselectrically conductive. An external hazardous electromagnetic signal 12(hazardous EMI), such as an electromagnetic pulse (EMP), induces anelectromagnetic signal on power line 104 as a pulse 14, which isdirected to electrical component (E.C.) 10. The electrical component(E.C.) 10 will be rendered inoperative if the magnitude of the voltagepulse 14 that reaches the electrical component (E.C.) 10 is too high byone or more failure mechanisms previously mentioned.

FIG. 2 shows a schematic view, not to scale, of a protected component100 (shown as “P.C.” in the figures), a power line 104 and a singleconductive impedance transition element (CITE) 106. CITE 106 introducesa deliberately-created frequency dependent mismatch of impedance along apower line 104 as a means or technique to protect the protectedcomponent (P.C.) 100 from the effects of a hazardous EMI. RepresentativeCITE 106 is shown schematically, and more detailed embodiments aredescribed below and illustrated in subsequent figures. The CITE 106 iselectrically conductive (e.g., formed of a metal such as aluminum,copper, stainless steel, a ferrite, some combination thereof, or otherconductive material) and has a first side 107 that faces away from theprotected component (P.C.) 100 towards a length of power line 104.Generally, the CITEs are structured such that one side of the elementmaximizes the diameter ratio between the element and the power line,which is termed the “first” side. During installation, the first side ofthe CITE is installed to face away from the protected component. Thereis an abrupt impedance mismatch between the first side 107 of the CITE106 and an axially adjacent portion of power line 104. It is noted thata single CITE will not give 100% reflection of the unwanted highfrequency components, and to achieve this, a more complex structure,such as is shown in FIGS. 3-8 is required and is described below. It isnoted that FIGS. 2-5 refer to one end of the power line with a singleprotected component. It is also noted that all signals travel on theconductor of the power line even though they are shown spatiallydisplaced from the power line for the sake of clarity.

A potentially damaging EMI signal 108 is induced (or in some cases,injected) on power line 104 by an external hazardous EMI 109 (e.g., EMP)that impacts the power line 104. Signal 108 is also referred to hereinas being a “transient induced signal 108”. The deliberate impedancemismatch introduced by the presence of the CITE 106 along the power line104 causes the first side 107 of CITE 106 to reflect a first portion 110of the transient induced signal 108 away from protected component (P.C.)100. Reflected portion 110 is inverted in polarity compared to thetransient induced signal 108 due to the mentioned reflection. A secondportion 112 of lesser amplitude of transient induced signal 108 istransmitted toward the protected component 100. The first portion 110which is transmitted away from the protected component is much larger(in amplitude) than the second portion, with the ratio being a functionof the degree of impedance mismatch. It should be understood that FIG. 2is simplified (as are similar figures) in regard to the depiction of atransient electromagnetic interference signals and depictions oftransmitted and reflected portions of transient electromagneticinterference signals. In FIG. 2, for instance, transient induced signal108 and the reflected first portion 110 of the transient induced signalappear to travel along separate paths, shown as separated by a verticaldistance. However, these signals 108, 110 actually travel in oppositedirections along overlapping paths that include power line 104.Furthermore, only a few, representative transmitted and reflectedportions of a transient electromagnetic interference signal 108 areshown in FIG. 2 (and in similar figures), for simplicity ofillustration. It is noted that the configuration of FIG. 2, while viableand operable, is not the preferred embodiment and is provided here,largely for exemplary purposes.

The design and placement of CITE 106 (and any other CITEs) on power line104 is intended to assure that the voltage applied across protectedcomponent (P.C.) 100 is sufficiently low as to avoid the destructiveconsequence of rendering such component inoperative. As mentioned above,the frequency dependent impedance mismatch (due to the CITE 106) alsoavoids reflection of voltage on power line 104, at the fundamentalfrequency of the current that supplies electrical power on the powerline, away from protected component (P.C.) 100. Such fundamentalfrequency may typically be 50, 60 or 400 Hz, for example.

One useful guideline for determining a maximal threshold voltage for theportion 112 of the transient induced signal 108 that is transmitted tothe protected component (P.C.) 100 is the transnational standard “BasicInsulation Level” (BIL), which is used globally as a metric forprotecting electrical components coupled to the electrical grid. As isknown, the insulation of equipment of a system must be designed towithstand a certain minimum voltage before an impulse (e.g. lightningimpulse) overvoltage gets discharged through surge protecting devicesand the like. Therefore, the operating voltage level of surge protectingdevices should be lower than the minimum voltage withstanding level ofthe equipment. This minimum voltage rating is defined as the BIL orbasic insulation level of the electrical equipment. Often, the BIL issix to seven times higher than the operating voltage level of surgeprotecting devices to fully ensure that the electrical equipment isprotected. It is noted that the multiple for BIL is dependent on theoperating voltage and decreases as the operating voltage increases.

Thus, the one or more CITEs are positioned sufficiently proximate to theprotected equipment (P.C.) 100 such that the portion 112 that passesthrough the CITE(s) to the protected equipment (P.C.) 100 is within theBIL rating (or some other set criteria or threshold) for such equipment.

As also discussed herein, the protected component (P.C.) 100 can takeany number of different forms across a wide spectrum of applications.For example, the protected component (P.C.) 100 can be in the form of aresidence (home) or a subcomponent thereof or can be in the form ofindustrial power equipment, such as substation or generator, etc.

FIG. 3 shows another embodiment of a power line 104 onto which two CITEs120, 122 are coupled. Each CITE 120, 122 has a first side that isoriented away from the protected component (P.C.) 100, and a second sideoriented toward the protected component (P.C.) 100. The first side ofCITE 120 and the first side of CITE 122 face each other across a sectionof the power line 104 and form a decaying resonator 125 for dissipatingenergy of the transient induced signals. A transient induced signal 126is induced on the power line 104 by an external hazardous EMI 127. Aportion of transient induced signal 126 passes to the left through CITE122 as a transmitted portion 128. Another portion of the transientinduced signal is reflected from the second side of CITE 122 as areflected portion 134. A portion of transmitted portion 128 that passesthrough CITE 122 is reflected to the right from the first side of CITE120 as a reflected portion 130. A portion of the reflected portion 130passes through CITE 122 as a transmitted portion 131. Another portion oftransmitted portion 128 passes to the left through CITE 120 astransmitted portion 132. The transmitted portions of the signal from thereceipt of the hazardous EMI 127, through induced signal 126 andtransmitted portions 128, 132 to protected component 100 are encircledby dashed box 150.

A portion of reflected portion 130 is reflected to the left from thefirst side of CITE 122 as further reflected portion 136. A portion ofreflected portion 136 passes to the left through CITE 120 as transmittedportion 140. Another portion of reflected portion 136 is reflected tothe right from the first side of CITE 120 as further reflected portion138. As the signal is reflected, the further reflected portions areattenuated compared to incident portions. For example, reflected portion138 is attenuated compared to reflected portion 136. A portion ofreflected portion 138 passes to the right through CITE 122 as atransmitted portion 142. The main transmitted components of the inducedsignal starting with portion external hazardous EMI 127, and includingthe induced signal on the power line 126, the portion 128 of signal 126transmitted initially through CITE 122, and the portion 132 of signal128 that is transmitted through CITE 120, are outlined in a dashedrectangular box 150. It will be appreciated that the terminology “left”and “right” is used only for convenience in describing the system shownin FIG. 3 and the relative arrangement of parts and relative directionof travel of the various signals.

As discussed herein, the CITEs 120, 122 can be spaced apart from oneanother a prescribed distance the value of which depends upon a numberof operating parameters, such as the type of power line 104, etc. Asdescribed below, the CITEs can be constructed so as to provide aninternal spacer or guide that automatically positions the CITEs at thedesired distance apart from one another.

It can be appreciated from FIG. 3 and the foregoing paragraph that aninitial transmitted portion causes a cascade of further reflectedportions; and in particular, the transmitted portion 128 causesreflected portion 130, which, in turn, gives rise to the furtherreflected portion 136, which further gives rise to further reflectedportion 138. FIG. 3 schematically illustrates each of the reflectedportions becoming successively diminished in intensity. As a result,CITEs 120 and 122 form a decaying resonator 125 for harmlesslydissipating energy of a transient induced signal resulting from exposureto hazardous EMI.

In FIG. 3, signals 131, 134 and 142 travel from CITE 122 to the rightalong the power line 104, where their energies are harmlessly dissipatedas heat in the power line. Within decaying resonator 125, the decayingresonant reflections of portions of transient induced signal 126 alsodissipate harmlessly as heat in power line 104. The respective voltagesof portions 132 and 140, directed from CITE 120 to protected component100 are kept sufficiently low to avoid rendering protected component 100inoperative and/or damaged. It should be appreciated that the spacing ofthe CITEs can allow either constructive or destructive interference; butit would be obvious to those of ordinary skill in the art thatconstructive interference at the frequencies of interest is to beavoided (see the discussion of constructive and destructive interferenceabove).

In the embodiment depicted in FIG. 3 the external EMI induces a signalto the right of both of the CITEs 120, 122. FIG. 4 is a schematicillustration of a different scenario in which the hazardous EMI strikesthe portion of the power line between the CITEs 120, 122. FIG. 4illustrates the transmitted portions in dashed box 150 a as a basis forcomparison to box 150 in FIG. 3. As can be discerned, in FIG. 4, unlikeFIG. 3, the indicated hazardous EMI is received at a section of thepower line between CITEs 120 and 122. A transient electromagnetic signal160 is induced on power line 104 by the hazardous EMI 162, and atransmitted portion 165 of the signal passes through CITE 120 toward theelectrical component (not shown in FIG. 4).

It is typically desirable to keep the length of power line 104 betweenprotected component (P.C.) 100 and the first CITE (i.e., 120) as shortas practical. As the probability of impact from external hazardous EMIis proportional to the length of the exposed power line, this limitsexposure of the foregoing length of power line 104 to transientelectromagnetic signals (induced signals) and the consequent likelihoodof this length being impacted by external hazardous EMI. As an example,if the power line extends between first and second transformers, one ormore and preferably a plurality of CITEs should be located at both endsof the power line such that a first set of CITEs is located proximatethe first transformer and a second set of CITEs is located proximate thesecond transformer with both sets of CITEs protecting the first andsecond transformers in the manner described herein. Of course, it willbe appreciated that instead of being transformers, the ends of the powerline can be connected to any protected electrical component, such as theexemplary ones described herein as well as others.

FIG. 5 is a schematic view of another embodiment of the presentdisclosure in which three CITEs are coupled to a power line 104 toprotect electrical components from the transient induced signalsoriginating from a transient electromagnetic disturbance. In thisembodiment, CITEs 170, 172, 174 form two decaying resonators, a firstresonator 178 between CITEs 170 and 172, and a second resonator 179between CITEs 172 and 174.

In FIG. 5, the same convention as above applies so that CITEs 170, 172,174 have first sides that are oriented away from the protected component(P.C.) 100 and second sides that are oriented toward the protectedcomponent (P.C.) 100.

In FIG. 5, external hazardous EMI 182 induces or injects signal 180 onpower line 104. A portion of signal 180 is reflected the first side fromCITE 174 to the right as reflected portion 184. A further portion oftransient electromagnetic (induced or injected) signal 180 istransmitted to the left through CITE 174 as transmitted portion 186. Inturn, a portion of the transmitted portion 186 reaches the first side ofCITE 172 and is reflected back to the right as a reflected portion 188.Another portion of the transmitted portion 186 passes to the leftthrough CITE 172 as the transmitted portion 187. A portion of thetransmitted portion 187 is further transmitted through CITE 170 as atransmitted signal 198. It is again noted that in terms of amplitude,transmitted portion 186 has a higher amplitude than transmitted portion187, which in turn has a higher amplitude than portion 198. Anotherportion of the transmitted portion 187 is reflected to the right by CITE170 as reflected portion 195. When the reflected portion 188 reaches thesecond side of CITE 174, a first portion of the signal is transmitted insignal 190 and a second portion is reflected to the left as signal 192.A first portion of signal 192, directed to the left is transmittedthrough CITE 172 as signal 194, while a second portion of signal 192 isreflected at the first side of CITE 172 as signal 196. When signal 194reaches the first side of CITE 170, a first portion of the signal isreflected as signal 200 and a second portion is transmitted through CITE170 as transmitted portion 202. In addition, when signal 196 reaches thesecond side of CITE 174, a portion of the signal is transmitted throughCITE 174 as transmitted portion 197.

The respective voltages of portions 198 and 202 are the finaltransmitted portions which are kept sufficiently low to avoid renderingprotected component (P.C.) 100 inoperative. Transmitted portions 184,190 and 197, which are directed to the right from CITE 122, dissipatetheir energy along power line 104 as heat.

In FIG. 5, the use of two decaying resonators 178 and 179 allows fordissipation of more energy of a transient electromagnetic interferencesignal, in comparison to the use of a single decaying resonator 125shown in FIG. 3 because of the larger number of passes of reflected andtransmitted signals between the CITEs, which increases heat dissipationalong the power line. Accordingly, the use of multiple pairs of decayingresonators can aid in minimizing any portion of a transient inducedsignal that reaches the protected component 100. It can be appreciatedthat the CITE structures are not, in and of themselves, intended to actas heat sinks, although they may. Rather, the heat is anticipated to bedissipated by the power line 104 itself by radiative processes.

FIG. 6 is a schematic view of another embodiment in which CITEsaccording to the present disclosure are used on a power line having afirst protected component 201 and a second protected component 203 atthe right end of the power line. Thus, in contrast to FIGS. 2-5, FIGS.6-8 illustrate both ends of the power line, each having respectiveprotected components 201. 203. In the example embodiment of FIG. 6, thefirst and second protected components are transformers. It is to beunderstood that they can be other components (as defined above) as well.In FIG. 6, variable CITE element 230 represents a variable number (1 toN) of CITEs and CITE groups associated with protected component 201, andvariable CITE element 232 represents a variable number n (from 1 to N)of CITEs associated with protected component 203. The variable CITEelement 230 is also shown separately to the right to illustrate theindividual elements (1 to N) of the variable CITE. Each element 230, 232includes a number of adjacent decaying resonators equal to the number ofCITEs in the element minus 1 (n−1). For example, if there are threeCITEs numbered 1, 2 and 3 positioned on a power line in series, therewill be a decaying resonator between CITEs 1 and 2, and another decayingresonator between CITEs 2 and 3. In the example shown in FIG. 6,resonator 235-1 is disposed between CITEs 1 and 2, and resonator 235-2is disposed between CITEs 2 and 3 of an exemplary variable CITE element.

FIG. 7 is a schematic view of another embodiment similar to FIG. 6 thatincludes more locations for installing variable CITE elements comprisingone or more CITEs. For example, elements 240, 242, 244, 246, 248, 250,252, 254 are coupled to the power line 104, between protected components100, 102. Again, each of the variable CITE elements 240-254 can contain1 to N CITEs. FIG. 7 has a legend that indicates that each of thevariable CITE elements 240-252 include a number of adjacent decayingresonators equal to the number of CITEs minus one (n−1). In the exampleshown in FIG. 7, resonator 235-3 appears between CITEs 1 and 2, andresonator 235-4 appears between CITEs 2 and 3 of an exemplary variableCITE element. The large number of CITEs that can be combined in thearrangement shown in FIG. 7 can provide a large number of decayingresonators to dissipate any signals induced by hazardous EMI. Forinstance, if variable CITE elements 240 and 242, which are situatedproximate to each other on the power line each include 3 CITEs, thetotal number of CITEs in the general location of elements 240, 242 is 6CITEs which would provide 5 decaying resonators therebetween.

FIG. 8 is a schematic view of another embodiment in which CITEs arearranged in groups of three along the power line 104. The CITEs withinthe groups are spaced in relatively close proximity to each other (e.g.,between about 1 centimeters and 10,000 centimeters); such spacing isreferred to hereinafter as intra-group spacing. CITEs 260, 261 and 262form a first group; CITEs 265, 266 and 267 form a second group; CITEs270, 271 and 272 form a third group; and CITEs 275, 276 and 277 form afourth group. Each of the foregoing groups of three CITEs can beseparated from an adjacent group of three CITEs by a larger inter-groupdistance compared to the intra-group spacing. The intra-group spacingand the inter-group distance are selected, as known to those of ordinaryskill in the art, to avoid creating constructive interference asdetermined by the speed of the induced signal on the power line, whichis some portion of the speed of light, as determined by the actualvoltage compared to the voltage levels necessary to achieve relativisticspeeds, as is known to a person skilled in the art. It is noted that thespeed of light in a vacuum is approximately one foot per nanosecond. Onan electrical power transmission line (e.g., line 104) of the typecontemplated herein, the speed of an electromagnetic wave is slower, onthe order of about one foot per 1.25 to 7 nanoseconds, depending on anumber of physical considerations. Selecting the spacing between eachCITE of a decaying resonator based on the reduced speed of anelectromagnetic wave on an electrical transmission line gives rise to anoptimal distance between each CITE of a decaying resonator. In someembodiments, the inter-resonator spacing is about 800 to about 1200feet; however, it will be appreciated that this range is merelyexemplary in nature and not limiting. The propagation of pulses in thistype of transmission line is well known and is discussed in textbooks onelectromagnetic pulse theory.

FIG. 8 also shows adjacent decaying resonators that are intra group(i.e., 235-5 and 235-6 in the first group, 235-8 and 235-9 in the secondgroup, 235-11 and 235-12 in the third group, and 235-14 and 235-15 inthe fourth group), and between the groups (i.e., 235-7, 235-10, 235-13).

A pair of CITEs of a decaying resonator can be nested within anotherpair of CITEs of another decaying resonator. For instance, in FIG. 8,CITE 262 of the first group and CITE 265 of the second group defineresonator 235-7 therebetween, while CITE 261 of the first group and CITE266 of the second group can be considered to define a large resonator235-15 that contains resonator 235-7. The nesting of CITE's in theforegoing manner increases the degree of attenuation of transientinduced signals. This gives a convenient method of designing the system.One takes the maximum amplitude of an induced signal that the system isdesigned to protect against and divides it by the attenuation factor pernested pair of CITEs of decaying resonators to get the number of nestedsets required.

Comparison to Traditional Low Pass Filters

In addition, the CITEs of the present disclosure have useful propertiesin comparison to conventional low pass filters. The CITEs of the presentdisclosure can be electrically described as a low Q factor low passfilter. The Q factor, which is the ratio of reactance to resistance,describes how underdamped an oscillator or resonator is, andcharacterizes a resonator's bandwidth relative to its center frequency.Higher Q indicates a lower rate of energy loss relative to the storedenergy of the resonator; the oscillations die out more slowly. Normally,filters are designed to have as high a Q factor as possible, but thepresent invention is specifically optimized for a low Q factor becausethat it is the optimal configuration for having the energy trapped bythe filter to be dissipated by the filter. Additionally, the CITEs ofthe present invention distinguish over traditional low pass filters inthat the CITEs have a non-resonant design, operate achromatically andhave a distinctive and unique frequency response curve. It can beappreciated that a CITE is designed to reflect some portion of theunwanted energy where a conventional filter is designed to absorb itinternally as heat.

Conventional low pass filters typically use inductors, capacitors andresistors to form various types of resonant circuits. By using variouscombinations of these types of components, it is possible to buildfilters of almost any transfer function. The problem with this approachis that, in common power transmission and distribution power systemsthat operate 50 to 60 Hertz, and at the conventional AC voltages andcurrents, the individual components become very large, unwieldy, andexpensive. The present invention resolves this by avoiding the use ofinductors, capacitors, or resistors and instead substitutessignificantly mismatched conductive impedance transition elements(CITEs). The CITEs of the present disclosure are distinguished overtraditional low pass filter designs due to their use of selectiveimpedance mismatch to create reflections of unwanted portions of thesignal, as opposed to the use of tuned resonant electronic circuitscomprised of inductors, capacitors and/or resistors in any combinationwhich simply absorb unwanted portions of the signal.

The CITEs of the present invention provide a more achromatic frequencyresponse in that frequencies under about one megahertz are passedunopposed while higher frequencies are selectively attenuated. Thehigher the frequency, the higher the attenuation factor, without theneed for changing any component values as would be the case withconventional filter designs. Using multiple decaying resonators provideseven higher attenuation of the higher frequency components. The designmethodology described herein provides a nearly step function frequencyresponse.

It is noted that low pass filters, historically, have not been used forlightning suppression due to the large size and cost of the componentsinvolved.

A system with low “Q”, quality factor (Q<½) is said to be overdamped.Such a system does not sustain oscillations well, but, when displacedfrom its equilibrium steady-state output, it returns to it byexponential decay, approaching the steady state value asymptotically. Ithas an impulse response that is the sum of two decaying exponentialfunctions with different rates of decay. As the quality factordecreases, the slower decay mode becomes stronger relative to the fastermode and dominates the system's response resulting in a slower system. Asecond-order low-pass filter with a very low quality factor has a nearlyfirst-order step response; the system's output responds to a step inputby slowly rising toward an asymptote.

As applied to the present invention in relation to an E1 pulse, a filterwith a low Q factor is desirable because it is allows the unwantedenergy from a trapped EMP or other transient electromagnetic disturbanceto die out in a decaying resonator(s) and be dissipated as heat. As aresult of the extremely short pulse width, typically less than 500nanoseconds for E1 pulses, it is desirable to make use of multipledecaying resonators to further decrease the Q factor of the device.

CITE Embodiments

As discussed herein, one of the components of the present system is theimpedance transition element (CITE) which is typically arranged in a setof preferably at least two CITEs.

Accordingly, the conductive impedance transition element (CITE) thatforms one side of a decaying resonator can be implemented as aconductive disk that is larger in diameter than the power line itsurrounds, wherein the conductive disk is electrically coupled to thepower line. As mentioned above, the resulting difference in diametersbetween the CITE and an adjoining portion of power line creates astructure that exhibits a high VSWR for high frequencies of a transientelectromagnetic (induced) signal as a result of the ratio of mismatchedimpedances between the CITEs and the adjacent portion of the power line.

One exemplary embodiment of an CITE according to the present disclosure,and parts thereof, are described in connection with FIGS. 9-15. FIG. 9is a plan view of one side of a CITE 300. The CITE 300 is formed overallin the shape of a disk, having an opening in the form of a central hole302. The CITE 300 is formed of a first (e.g., upper) part 305 and asecond (e.g., lower) part 310 that are coupled by a hinge element 315 soas to permit the first part 305 and the second part 310 to move betweenan open position in which the two parts 305, 310 are at least partiallyseparated from one another, and a closed position that is shown in FIG.9.

As shown in FIG. 9, the CITE 300 has an outer peripheral portion thatcan have a toroidal shape, as shown, and an intermediate portion, and acenter portion in which the center hole 302 is formed. Since the CITE300 is defined by the first and second parts 305, 310, each of theseparts has an outer peripheral portion, the intermediate portion, and thecenter portion. The outer peripheral portion thus includes rounded edgesthat are intended to eliminate and/or control coronal discharge.

In the depicted embodiment, the upper component has an outer peripheralsection 312 of increased width and the lower component has acorresponding outer peripheral section 313 of increased width. In oneimplementation, the outer peripheral section 312 is approximately ½ of atorus and the outer peripheral section 313 is likewise approximatelyhalf of a torus so that when combined, the two sections 312, 313 definea generally toroidal shape along the outer periphery of the CITE 300. Inother words, these sections 312, 313 have rounded surfaces. It is notedthat the inner surfaces of 312 and 313 may be textured or even spiked(not shown in FIGS. 9-11 but shown in FIGS. 12-15) to pierce andincrease electrical contact with the power conductor that is containedby these elements.

The first part 305 has a middle section 314 recessed with respect to theouter peripheral section 312 and the second part 310 has a correspondingmiddle section 315 that is recessed with respect to the outer peripheralsection 313. Compared to the toroidal shape of the outer peripheralsection, the middle sections 312, 314 can be planar in form andgenerally have a semicircular shape.

The first part 305 also includes a protruding fastening hub 316positioned on the second side of the CITE which faces toward theprotected component (extending out of the page in the view of FIG. 9)and the second part 310 includes a corresponding protruding fasteninghub 317 also positioned on the second side of the CITE. As shown, thefastening hubs 316, 317 form a lip around the central hole 302. Thefastening hubs are used to securely couple the CITEs to the power lineand also to securely fasten the upper and lower parts 305, 310 togetheras will be described further below with reference to FIGS. 10 and 12. Inthe view shown in FIG. 9, the upper component 305 is seated upon thelower component.

Via the hinge element 315, the upper component 305 can pivot in acounterclockwise direction away from the lower component 310 as shown inFIG. 10. When pivoted, a gap or space is opened up between the uppercomponent 305 and the lower component 310. As shown, the opening of thisgap also provides access to the center opening that is defined betweenthe fastening hubs 316, 317 that receives the power line (cable) aboutwhich the CITE is disposed. Also depicted in FIG. 10 are clearance hole307 and threaded hole 308 through respective feet sections 321, 327 offastening hubs 316 and 317. Returning again to the view of FIG. 9, whenthe upper and lower sections are brought together (unpivoted) the boreholes 307, 308 match and form a continuous hole through which afastening element such as a screw or bolt can be inserted, locking theupper and lower sections of the CITE together. An exemplary screw head303 is shown in FIG. 9 to represent such a fastening element. In someembodiments, the sections 321, 327 can include additional bore holes forreceiving additional screws or bolts to further ensure a tightconnection between the fastening hubs of the upper and lower parts ofthe CITE. A rivet can also be used, in which case threaded elements arenot needed. Also shown in FIG. 12 is the inclined contact surface 328 ofthe lower component which seats with a complementary contact surface ofthe upper component 305 (not shown).

In some embodiments, the fastening hubs 316, 317 are positioned on oneside of the CITE 300 (i.e., protrude outwardly perpendicular to theplane of the disc in one direction) and when multiple CITEs 300 arecombined in series, the fastening hubs can act as spacers since twoadjacent CITEs 300 can be arranged such that the protruding fasteninghubs 316, 317 contact, or are in close proximity to, an opposite face ofthe adjacent CITE 300. Thus, when the two adjacent CITEs 300 are pushedinto contact with one another, the fastening hubs sections 316, 317 candetermine the distance between the two adjacent CITEs 300. The length ofthe fastening hubs 316, 317 can be used to define the distance (gap)between the two adjacent CITEs 300 in embodiments in which groups ofCITEs are grouped together in a unit. The transmitted transient inducedsignal that moves from a first CITE 300 toward the protected electricalcomponent thus encounters a second CITE 300 that is located theprescribed set distance (defined as the length of the protruding innersections 316, 317) away from the first CITE 300. In this way, a seriesof CITEs 300 can be arranged with controlled spacing along the powerline. While it is envisioned that the spacing between adjacent CITEs 300in the series can be uniform, it will also be appreciated that thespacing can be non-uniform in that there can be at least a firstdistance between two adjacent CITEs 300 and a different second distancebetween two other adjacent CITEs 300. Non-uniform spacing of CITEs 300can be useful in providing multiple destructive interference conditionsalong the power line 104. As the incoming hazardous EMI can havedifferent spectral components, having non-uniform spacing ensuresdestructive interference over a range of different frequencies.

FIG. 11 is a hinge end view of the CITE shown in FIG. 10 in which theupper and lower components 305, 310 have been pivoted away from theseated position. In this view it can be seen that the bottom surface 322of the upper component has a jagged profile and the top surface 324 ofthe lower component has a complimentary jagged profile adapted tocooperatively engage to the lower surface of the upper component.However, the surfaces 322, 324 do not engage in a flush manner, leavinga notch 325 that extends inwardly into the CITE

FIG. 12 is a perspective view of the CITE 300 in a slightly pivotedposition, which more clearly illustrates fastening hubs 316, 317.Fastening hub 316 includes a semicircular lip section 319 and a footrectangular “foot” section 321. Similarly, fastening hub 317 includes asemicircular lip section 323 and a rectangular foot section 327. The“feet” sections 321 a, 327 a of the respective fastening hubs have adifferent fastening mechanism from that shown in FIGS. 9 and 10. In thisembodiment, the bottom surface of foot section 321 a (of fastening hub316) includes a ratchet element 343 with flexible teeth having theability to bend and snap in place with respect to matching teethpositioned in a receptacle 345 in the foot section 327 b of fasteninghub 317. The manufacturing methods and material properties used for suchratcheting fasteners are known to those of skill in the art. When theCITE is being closed and ratchet element 343 enters the receptacle 345the upper and lower sections 305, 310 are secured together in place.Also shown in FIG. 12 is the inclined contact surface 328 of the lowercomponent which seats with a complementary contact surface of the uppercomponent 305 (not shown).

The inner surfaces of the semicircular sections 319, 323 of thefastening hubs include sharp incision elements 341 (identifiedcollectively). The incision elements are adapted to cut into the outersurface of the power line when the CITE is mounted and the fasteninghubs 316, 317 close around the power line. By cutting into the powerline, a firm, secure, and conductive connection between CITE and thepower line is ensured. The incision elements 341 can be formed inpyramidal form as shown, as spikes, or in other shapes that wouldsupport the functional purpose of the incision elements as known tothose of ordinary skill in the art. The number and sizes of theindividual incision elements used can vary based on the knowncharacteristics of the power line.

To prevent arcing, a conductive paste is applied to all joints in theCITE and to the interface between the CITE and the power line. Forexample, during installation on a power line, a conductive paste such asCondutoLube, manufactured by Cool Amp ConductoLube Co., of Lake Oswego,Oreg., or the equivalent, can be applied on surfaces 328 and to allother interfaces between the upper and lower components 305, 310. In theembodiment shown, the conductive paste is also applied to the hingesurfaces 322, 324 to prevent arcing at the hinge element as well. Oncethe CITE has been mounted around the power line, and the power line isposition in the central hole 302 of the CITE, conductive paste can beapplied around the edge of the central hole to ensure a uniformconductive connection between the CITE and the power line.

FIG. 13 is a perspective view of the lower component 310 of the CITE andFIG. 14 is a perspective view of the upper component 310. The componentviews of FIGS. 13 and 14 more clearly illustrate the inclined contactsurfaces 328, 329 on which the upper and lower components connect. Bothsurfaces 328, 329 are discontinuous and broken in the middle to providefor the central hole 302. FIG. 15 is a longitudinal cross-sectional viewtaken through axis 15-15 in FIG. 11. The view of FIG. 15 illustratesthat most of the outer sections 312, 313, other than the hinge element315 of the respective upper and lower components are hollow, which helpsreduce the weight and cost of the CITE.

The construction of the CITE 300 thus allows for the easy opening of itsstructure to allow receipt of a cable and then the sealed closing of theupper and lower components 305, 310 results in the capturing of thecable, thereby causing the CITE 300 to be securely coupled to the cable.

In another embodiment of a CITE 1300, shown in FIGS. 28A and 28B, theupper component of the CITE, similar to the upper component of theembodiments shown in FIGS. 9-16 has a tongue element 355 that protrudesfrom a bottom surface of the component. The lower component includes acomplementary groove 357 sized to tightly receive the tongue elementwith a small amount of tolerance, in order to achieve a solid electricalcontact. The tongue-groove pair, together with the fastening hub, aidsin securing the upper and lower components together after the CITE ismounted on a power line.

FIG. 16 is a perspective view of another embodiment of a CITE accordingto the present disclosure. The CITE 600 includes upper and lowersections 605, 610 that are not attached at a hinge element. In theembodiment shown, fastening hub 616 of section 605 comprises asemicircular lip 621 which forms an edge around a central hole throughthe cite 602, and two feet sections 623, 624 positioned on either sideof the semicircular lip 621. Similarly, fastening hub 617 of section 610comprises a semicircular lip 631 positioned around central hole 602 andtwo feet sections 633, 634. Foot section 623 of the upper sectioncouples to foot section 633 of the lower section, and foot section 624of the upper section couples to foot section 634 of the lower section tosecure the upper and lower sections to each other. In a preferredembodiment, matching threaded bore holes are drilled through sections623/633 and 624/634 allowing screws, bolts, rivets or similar fasteningelements to extend through and securely join the matching sections. Uponinstallation on a power line, conductive paste is applied to the entireinterface between the upper and lower sections to prevent arcing anypossible gaps between the sections.

While in the embodiments shown in FIGS. 9-16 the cross-sectional shapeof the CITE is circular, one or more of the CITEs employed can haveother shapes including elliptical, polygonal, and non-uninform (e.g.,asymmetrical and/or irregular). In all such embodiments, thecross-sectional dimensions of the CITEs are larger than the diameter ofthe power line upon which they are mounted, and deliberate impedancemismatch occurs as in the case of circular CITEs.

Use of CITE Elements for Signaling Purposes

The CITEs of the embodiments shown in FIGS. 9-16 can be usefully adaptedto signal the presence of a high voltage line, for example in airportsand other facilities in which it is useful to call out the presence ofhigh voltage power lines for distant visibility. In one implementationof a CITE 1000, shown in FIG. 24, walls of the outer peripheral “torus”section 1010 can be made, at least in part, of a transparent material.As the torus sections are hollow, they can be filled with a gas, such asneon, which fluoresces in the presence of a high electric field.Fluorescence radiation e.g., 1015 emanating from the outer peripheralsection 1010 is shown. When a CITE including a transparent (or partiallytransparent) torus filled with such as gas is mounted onto a highvoltage power line, the electric field produced by the power line causesthe gas to fluoresce. This fluorescence makes the CITE visible fromafar, and thereby signals the presence of the high voltage power line towhich the CITE is mounted.

It is noted that the normal components of a gas discharge light need tobe present. Therefore, a getter pump is desirable to maintain the purityof the fluorescing gas which is preferably a noble gas such as neon orargon.

Additional CITE Embodiments

FIG. 17 shows an alternative embodiment of an impedance transitionelement (CITE), numbered 500. As with all CITEs described herein, CITE500 is conductive and makes conductive contact with power line 104,which it encircles (surrounds). CITE 500 has a generally flat face 505shown on the right, and a conically surface 510 which inclines away fromsurface 510 toward the left. The flat face 505, as the first reflectingsurface, presents an abrupt impedance change compared to the impedanceof the adjacent portion of power line 104 (to the right of face 505) dueto the abrupt change in diameter. The conically shaped face on the leftpresents a more gradual change in impedance compared to the impedance ofthe adjacent portion of power line 104 (to the left of flat face 510).Accordingly, the flat face 505 is used for reflecting a transientelectromagnetic interference signal. As with the previous embodiment,the CITE 500 functions as a result of it having a much greater diameter(dimensions) compared to the dimensions (diameter) of the power line.

FIGS. 18A-18C illustrate CITE embodiments having differentcross-sectional shapes. FIG. 18A shows an embodiment of a CITE 701having upper and lower sections 705, 710 that when assembled have anelliptical cross-sectional shape. FIG. 18B shows an embodiment of a CITE711 having upper and lower sections 715, 720 that when assembled have apolygonal (in this case hexagonal) shape and FIG. 18C shows anembodiment of a CITE 712 having upper and lower sections 725, 730 thatwhen assembled have an asymmetrical cross-sectional shape. In theembodiments shown, CITEs 701, 711 and 721 are otherwise similarstructurally to the embodiment shown in FIG. 16 (e.g., they each includea similar fastening hub with threaded elements on both lateral sides ofa central hole for mounting to a power line).

In many implementations, it is practical to form CITEs either totally orpartially from ferrite components. The use of ferrite offers a number ofbenefits, including reduction of physical size and decreased Q factor,but at increased cost. FIG. 21 shows another embodiment of a conductiveimpedance transition element (CITE) in the form of a ferrite beadlocated coaxially on power line 104. The geometry and electromagneticproperties of ferrite bead CITE 570 results in a relatively highimpedance for high-frequency signals that attenuate the relatively highfrequencies of signals induced by external hazardous EMI on a power lineand also of high frequency radio interference (RFI) electronic noise.The energy from these sources is either reflected back along power line104 toward the source of the induced signal or is dissipated aslow-level heat along the power line. Only in extreme cases is the heatnoticeable. It is noted that ferrites also absorb energy as well asreflecting some portion of it.

A CITE generally does not dissipate energy but, instead, producesreactance that impedes the flow of the relatively high frequencies of atransient electromagnetic interference signal. This reactance iscommonly referred to simply as impedance, although impedance can be anycombination of resistance and reactance. Ferrite concentrates themagnetic field and increases impedance and therefore reactance, whichimpedes or ‘filters out’ high frequency signals. Ferrite beads areregularly made in split configurations which facilitates installation onan existing power line.

If the ferrite component is so designed, it can produce an additionalloss in the form of resistance heating in the ferrite itself. The Qfactor of an inductor is the ratio between the its reactance andresistance at a given frequency. When the Q factor of a ferrite inductoris low, it has relatively high resistance and is therefore subject toresistive heating. Depending on the application, the resistive losscharacteristic of the ferrite may or may not be desired. A design of aferrite CITE that uses a ferrite bead to improve noise filtering (inaddition to protecting electrical components from a transientelectromagnetic interference signal) should take into account specificcharacteristics of a circuit including the ferrite CITE and also thefrequency range to block. Different ferrite materials have differentproperties with respect to frequency. A person of ordinary skill in theart will find that manufacturer's literature may be helpful in selectingthe most effective material for the frequency range. It is noted thatferrite structures consisting of two or more different ferritecompositions may be utilized to optimize both the reflective andabsorptive properties of the CITE. There are a variety of methods ofcombining two or more ferrite components that would be known to those ofskill in the art.

Regardless of the shape of conductive impedance transition elements(CITEs), it is important to note that multiple pairs of CITEs may beused to increase the attenuation of the reflected transientelectromagnetic interference signal. Such multiple pairs of impedancetransition elements constitute the preferred embodiment of the currentinvention. It is further noted that impedance transition elements aredesigned and formed so as to be consistent with good high voltageengineering practice to prevent or minimize the formation of arcs,coronal discharge, and electrical shorts. These shapes are well known topersons of ordinary skill in the high voltage arts.

Conductive impedance transition elements (CITEs) are simple physicalstructures which can be manufactured by a variety of methods. Thesemethods include, but are not limited to, machining, casting, diecasting, injection molding, forging, stamping, lost wax casting, powdermetallurgy and sintering, 3D additive manufacturing, profiling with awater jet, profiling with a laser, etc., and combinations of thesemethods. Additionally, the CITEs can be assembled from component parts,such as disks with anti-corona rings attached to the exterior perimeter,and a clamp mechanism attached to the center. The specific method(s)chosen will be routine to persons of ordinary skill in the art and wouldusually be based upon on most cost-effective method(s) for making thenumber of devices required over a given period of time, as well as themanufacturing processes available to the manufacturer.

In a number of the implementations, the CITE is assembled from upper andlower components, which are each manufactured separately. In otherembodiments, CITEs can be fabricated in other ways, including fromlongitudinal sections. FIGS. 22A and 22B are plan views illustrating amethod of assembling a CITE from two longitudinal sections. FIG. 22Ashows a front view of a disc-shaped first section 805. The front surfaceof the section shown defines a “plane of the section.” The first sectionhas a slot 808 that extends from the outer circumference of the disc tothe center. The diameter of slot 808 is set to allow a power line 804 tobe received into the slot as shown. A removable bracket 815 is shownplaced beneath in inner end of the slot 808 at the center of section805. The bracket includes clearance holes for receiving threadedelements 817, 818 such as screws or bolts. The back of section 805 cabinclude additional fastening elements (e.g., holes) for receivingfasteners such as screws or bolts that extend transversely,perpendicular to the plane of the section (not shown in FIG. 22A).

FIG. 22B is a rear view of a complementary disc-shaped second section820. The second section 820 is designed to be fitted to section 805 toassemble the CITE. Second section 820 includes slot 822 shaped similarlyto slot 808 of section 805 to receive the power line 804. A bracket 825,complementary to the bracket 815 of the top section is shown above theinner end of slot 822. Bracket 825 includes threaded holes 827, 828adapted to receive the threaded elements 817, 818 of the complementarybracket 815 of the first section. In this manner, the first section canbe secured to the second section with the brackets 815, 825 forming atight fit around the power line 804. In addition, the surface of thesecond section can include threaded holes e.g., 831, 832 for receivingadditional fastening elements. In this manner the sections can befastened together via the complementary brackets 815, 825 that fastenthe first and second sections in the plane of the sections, andadditionally via additional fastening elements that fasten the first andsecond sections along an orientation transverse to the plane of thesection.

In another embodiment, shown in FIG. 23, the CITE 900 is formed in theshape of a sphere 905 having a diameter greater than the diameter of thepower line 904. This is not the preferred form for a CITE, but thesphere also provides an impedance mismatch which causes reflection ofincoming hazardous EMI.

Further, the CITEs of the present invention are comprised of simplestructures that clamp on to existing power lines. They have no activeelectronic circuitry, nor do they contain any internal components thatcan be damaged or degraded during virtually any operational scenario.

Additionally, as a function of their physically simple design, impedancetransitional elements can be readily mass produced. Accordingly, theircost for a pair of CITEs that form a decaying resonator can be a smallfraction of the cost of other solutions. Further, because CITEs can bedesigned to be easily installed on live power lines, installation timeand costs can be substantially reduced compared to other technologies.The savings can be particularly significant because the supply of powerover the power line is not interrupted.

Absorber Elements

The CITE elements described above are conductive and do not absorb theenergy of incoming hazardous EMI. In the embodiments shown in FIG. 2-8,the energy of the incoming EMI is dissipated as heat along the powerline. To enhance the rate of dissipation and to reduce the amount ofenergy that the power line is required dissipates per unit time, one ormore absorber elements can be mounted to the power line in associationwith or in addition to the CITE elements. The absorber elements can beformed in a similar manner to the CITEs but are made from resistive orsemi-resistive (or semi-conductive) materials, such as graphene. Theresistive materials are designed to absorb energy from incominghazardous EMI and to convert the electromagnetic energy into heat. Theheat thus generated dissipates over time into the environment byradiative or conductive cooling. One or more absorber elements can beadded at regular or irregular intervals along the power line. In oneexample, in which groups of CITEs are assembled together, an absorberelement can be added to each assembly or positioned adjacent to eachassembly. This is only one example, and those of skill in the art canreadily appreciate that absorber elements can be added in variousnumbers and configurations consistent with their purpose of providingadditional heat dissipation capacity.

The absorber elements can be separate, standalone element, or, in someembodiments, the absorber elements can be integrated as part of the CITEelements. A mix of separate and integrated absorber elements can also beused. FIGS. 25A-C show disc elements in which the central portion of thedisc is made from different materials. In FIG. 25A, the central portion1025 is made from resistive or semi-conductive material such as graphenewhich acts as an absorber element. In FIG. 25B, the central portion 1035is made from a metal such as an aluminum. This embodiment is similar tothe CITEs described above with reference to FIGS. 9-16. FIG. 25C shows adisc element in which the central portion 1045 is made from ferriticmaterial which can act both as a reflector and absorber of incominghazardous EMI.

Another embodiment of an integrated CITE/absorber element is shown inFIGS. 26A and 26B. In this embodiment, one side of the CITE 1105includes a conductive central portion 1115 and the opposite side of theCITE 1110 includes an absorptive material (resistive or semi-conductive)in its central portion 1120 element. It is noted that the CITE assemblymay be composed of various combinations of conductive, absorptive, andferritic materials in an array of CITEs (such as is shown in FIG. 8) toachieve maximum suppression of the unwanted high frequency components ofthe incident signal.

Impedance Mismatching for Underground Power Cables

The embodiments above pertain to exposed, above-ground power lines. Asignificant number of power lines, particularly in metropolitan regions,are not exposed, but rather run underground. It would be useful toprovide impedance mismatch elements in underground cables to provideprotection for electrical and electronic components attached thereto.FIGS. 27A and 27B are, respectively, an axial cross-sectional view and alongitudinal cross-sectional view of a coaxial power cable 1200 havingperiodic variation in impedance according to the present disclosure. Thecable includes a core 1205 having one or more conductive wires, asemiconductive layer 1210 surrounding the core, a conductive shieldlayer 1215, and an insulating layer 1220 surrounding the shield layer.As shown in FIG. 27B, the semiconductive layer 110 has periodicvariation in content which corresponds to periodic variations(differentials) in impedance. For example, areas 1232 and 1234 havehigher resistance compared with respective adjacent regions 1233 and1235.

The adjacent regions of differential impedance create impedance mismatchinterfaces at which received hazardous EMI is reflected in a mannersimilar to the way induced signals along the above-ground powerline arereflected by the CITE elements.

It is noted that there are several methods of achieving the variationsin the impedance of the semiconductive layer. These include, but are notlimited to, varying the conductivity of the composition of thesemiconductive layer, varying the thickness of the semiconductor layer,and others as would be obvious to a person of ordinary skill in themanufacture of coaxial type cables.

As would be clear to those of ordinary skill in the art, the CITEsdescribed herein can be used in conjunction with other protective meansthat utilities use to protect against hazardous EMI, such as but notlimited, to vacuum tube devices.

The scope of the claims should not be limited by the preferredembodiments and examples described herein, but should be given thebroadest interpretation consistent with the written description as awhole. It will be apparent to a person of ordinary skill in the art thatthere are many possible variations that fall within the scope of thisspecification.

What is claimed is:
 1. A method of protecting a component coupled to a power line of an electrical power generation, transmission and distribution system from hazardous EMI comprising: deliberately creating an impedance mismatch by mounting a plurality of conductive impedance transition elements (CITEs) having a diameter greater than a diameter of the power line at a position between an extended length of the power line and the component; wherein a difference between the diameter of the CITEs and the power line intentionally causes an impedance mismatch between the two or more conductive impedance transition elements with adjacent portions of the power line, the impedance mismatch causing high-frequency components of a signal induced on the power line by the hazardous EMI to be reflected and dissipated by decaying resonators formed between pairs of the plurality of conductive impedance transition elements.
 2. The method of claim 1, wherein a ratio of the diameter of the plurality of conductive impedance transition elements to the diameter of the power line is in a range of about 1.5:1 to 100:1.
 3. The method of claim 2, wherein the ratio of the diameter of the plurality of conductive impedance transition elements to the diameter of the power line is preferably in a range of about 2:1 to 80:1.
 4. The method of claim 1, wherein the plurality of conductive impedance transition elements are formed in the shape of a disc.
 5. The method of claim 1, wherein the plurality of conductive impedance transition elements are grouped into subsets each having two or more elements, an intraelement spacing being uniform within the subsets.
 6. The method of claim 1, wherein at least one of the plurality of conductive impedance transition elements is positioned within 100 meters of the component to be protected.
 7. The method of claim 1, wherein the plurality of conductive impedance transition elements prevent at least 75 percent of the transient electromagnetic signal induced on the power line by the hazardous from reaching the component.
 8. The method of claim 1, wherein the hazardous EMI includes an electromagnetic pulse having a rise time in a range of 50 ps to 500 μs.
 9. The method of claim 1, further comprising arranging at least two of the plurality of conductive impedance transition elements at a distance from each other to provide decaying resonators for high-frequency components of the induced transient electromagnetic signal on the power line.
 10. The method of claim 1, further comprising arranging the plurality of conductive impedance transition elements at a non-uniform distances to provide decaying resonators for different spectral components of the induced transient electromagnetic signal on the power line.
 11. The method of claim 1, wherein the decaying resonators formed by pairs of conductive impedance transition elements have a low Q-factor for high-frequency components of the induced signal.
 12. The method of claim 1, wherein one or more of the plurality of conductive impedance transition elements (CITEs) are composed entirely, or in part, of ferrite material.
 13. The method of claim 1, further comprising: testing of a spacing between the plurality of conductive impedance transition elements to ensure destructive interference of a pulse of suitable risetime, pulse width and amplitude; and adjusting the spacing if the pulse signal is reduced when transmitted between the plurality of conductive impedance transition elements.
 14. The method of claim 1 further comprising increasing a distance separating the power line from any adjacent power lines allow for the installation of the plurality of conductive impedance transition elements on the power line without contacting the adjacent power lines.
 15. The method of claim 1, wherein the power line conveys a voltage with an amplitude of at least 100 Volts.
 16. The method of claim 1, further comprising including one or more absorber elements at a position between an extended length of the power line and the component.
 17. The method of claim 16, wherein the one or more absorber elements are integrated as a component into one or more of the plurality of CITEs.
 18. The method of claim 17, wherein the plurality of CITEs contain one or more of conductive metal, resistive or semiconductive absorptive material, and ferritic material.
 19. The method of claim 1, wherein the plurality of conductive impedance transition elements are mounted on a live power line.
 20. A device for preventing an electrical signal induced on a power line of an electrical power generation, transmission, and distribution system by hazardous EMI from reaching an electrical component connected to the power line, the device comprising: a plurality of conductive impedance transition elements that are mounted to the power line and have diameters that are greater than a diameter of the power line to deliberately create an impedance mismatch between the conductive impedance transition elements and adjacent portions of the power line; wherein the impedance mismatch causes the conductive impedance transition elements to reflect high-frequency components of a signal induced on the power line by hazardous EMI, and wherein the high-frequency components are reflected and dissipated as heat by decaying resonators formed between pairs of plurality of conductive impedance transition elements.
 21. The device of claim 20, wherein a magnitude of the impedance mismatch is dependent upon a frequency and permits low frequency spectral components of the induced transient electromagnetic signal to pass by the plurality of conductive impedance transition elements while reflecting the unwanted high-frequency spectral components of the induced transient electromagnetic signal from the plurality of conductive impedance transition elements.
 22. The device of claim 20, wherein one or more of the plurality of conductive impedance transition elements are composed entirely, or in part, of ferrite material.
 23. The device of claim 22, wherein one or more of the plurality of conductive impedance transition elements are composed of two or more different ferrite materials.
 24. The device of claim 20, wherein a ratio of the diameter of the plurality of conductive impedance transition elements to the diameter of the power line is in a range of about 1.5:1 to 100:1.
 25. The device of claim 24, wherein the ratio of the diameter of the plurality of conductive impedance transition elements to the diameter of the power line is preferably in a range of about 2:1 to 80:1.
 26. The device of claim 20, wherein each of the plurality of conductive impedance transition element comprises a first section and a second section, the first and second sections being coupled via a hinge element that allows the first and second sections to be pivoted with respect to each other at the hinge element.
 27. The device of claim 26, wherein each of the first part and the second part of the conductive impedance transition element includes a fastening hub including a center opening for receiving the power line, the fastening hubs of the first and second part being adapted to fasten together to secure the first and second part together when mounted on the power line.
 28. The device of claim 27, wherein the raised outer periphery has a toroidal shape.
 29. The device of claim 28, wherein the raised outer periphery comprises a hollow structure.
 30. The device of claim 29, wherein the hollow outer periphery has a transparent outer surface and is filled with a gas that fluoresces in response to a high electric field.
 31. The device of claim 26, wherein the fastening hubs of the first and second parts each include a semicircular portion and a rectangular foot portion, the foot portions having matching threaded holes adapted for receiving a fastening element.
 32. The device of claim 31, wherein the semicircular portions of the fastening hubs have inner surfaces bearing incision elements adapted for cutting into the power line and thereby securing the CITE to the power line.
 33. The device of claim 26 wherein the fastening hubs of the first part and second parts each include a semicircular portion and a rectangular foot portion, the foot portion of the first part having a ratchet element and the foot portion of the second part having a receptacle having features matching the ratcheting element, enabling the first and second parts to be fastened to each other.
 34. The device of claim 20, wherein the decaying resonators formed by pairs of conductive impedance transition elements have a low Q-factor for high-frequency components of the induced signal.
 35. The device of claim 20, wherein at least one of the plurality of CITEs is a circular in shape.
 36. The device of claim 20, wherein at least one of plurality of CITEs is non-circular in shape.
 37. The device of claim 36, wherein at least one of the plurality of CITEs has a non-circular shape is one of ellipsoid, polygonal and non-uniform in shape.
 38. The device of claim 36, wherein at least one of the plurality of CITEs has an asymmetrical shape.
 39. The device of claim 36, wherein at least one of the plurality of CITEs has a spherical shape.
 40. A method of protecting a component coupled to an underground power line of an electrical power generation, transmission and distribution system from hazardous EMI comprising: deliberately creating an impedance mismatch by introducing impedance variations in a semiconductive layer surrounding conductors of the power line; wherein a difference between impedance in sections of the semiconductor layer intentionally causes a differential impedance mismatch between the semiconductive layer and adjacent portions of the power line, the impedance mismatch causing high-frequency components of a signal induced on the power line by the hazardous EMI to be dissipated along the power line as heat. 